That's how i understand this.Imagine you have some parameter value (ex. 0-100%) and some limit (ex.50%).In DB you have value itself as real, and bool variable, that indicates that limit has been exceed.This can lead to such situation:1) you send value (49,9%) in 1st communication telegramm(withotubool-forexamplemaximumbytesintelegrammisreached) 2) value incerases over limit (50,1%)3) You send indication without value (because it was just sent)

As a result you get 49,9% + limit exceed for some time. Such data called inconsistent.

If you write real+bool in DB and then set flag, indicating that both are ready for data exchage they would be consistent (because you don't rewrite value untiltheyareread).

The manual of S7technology describe a procedure for read the data from a technology DB.

The procedure consist to watch a flag"UpdateFlag" for to be sure that the data consistency are right.

My question is: what means exactly "data consistency"?

A non consistent data is just a data taken in a different time respect to another?

Or a non consistent data could be a corrupted data?

I hope that my question has been clear

thanks to all and bye!

Hallo mzmo,non consistent data are from different time, eg. the speed is not from the same time as the position.I think the procedure is a theoretical behavor, described to be shurely on the right side. I never used it.But keep always in mind the data may be up to 18 ms old!I homeed a axis and looked for the actual position in the T-DB. Sometimes it showed (for a few cycles of OB1) still the old value, because the T-DB was not jet actualisated.